Trying to pry business away from the embattled New York Stock Exchange, the Nasdaq Stock Market e-mailed big investors, telling them they could trade faster and more quietly on Nasdaq than on the Big Board.

“Trade IBM on Nasdaq,” reads the subject line of the e-mail Nasdaq sent to mutual funds and traders more than a week ago. “Get nearly instantaneous executions” and “avoid specialists’ discretion” and “pre-trade information leakage.”

The NYSE, which announced in May it was investigating some specialists’ trading practices, has been under siege from regulators and now, competitors, who are trying to put a dent in its near monopoly.

The exchange has been looking into whether specialists, who keep an orderly market in a stock, are actually getting between buyers and sellers for their own profit rather than letting the two trade unimpeded.

The NYSE has also been barraged by scrutiny of its abysmal corporate governance record and for NYSE chief Dick Grasso’s pay package, which was close to $20 million in 2001 and $12 million in 2002.

Electronic trading system Instinet recently launched a similar campaign on CNBC. “Trade NYSE stocks with confidence . . . yes it’s possible,” says the ad, which first ran in the Wall Street Journal.

Institutional investors have long complained that the NYSE’s guarantee of “price improvement” often means improvement for the specialist – not for the trader trying to execute the trade.

The campaign “is a low- cost way for us to reach out to the buy-side community to let them know about the advantages of Nasdaq InterMarket,” Nasdaq spokesman Scott Peterson said, using Nasdaq’s brand name for trading other exchange’s shares.